1. Field of the Invention
The invention is directed to a pipe-bending press with a large bending length in closed frame construction. The press has a frame with side columns and upper and lower cross-pieces, wherein the bed or table carrying the lower bending tools is supported at the lower cross-piece while the upper bending tool, which is guided vertically at the side columns in a parallel manner, is supported via a plurality of identical piston/cylinder units arranged side by side so that it can be raised and lowered relative to the upper cross-piece. Additionally, the cylinder spaces of the piston/cylinder units are connected to a common pressure medium unit via a common control line.
2. Description of the Related Art
Such presses are known, for example, from DE-AS 10 72 948 or DE-AS 24 55 521. In such presses with closed frame-like columns, large bending moments result which require the table and bending tool to have very large moments of inertia the table and bending tool in order to keep the deflection or bending of these parts within permissible limits. Even when the upper and lower cross-pieces of the pipe-bending press have correspondingly large dimensions, a bending up of the frame cannot be ruled out, even in the lower region of the press, that is, in the region of the table receiving the lower bending tools. The steps provided in the prior art also cannot prevent the press frame from bending up, particularly not without a disproportionate increase in the overall size or height of the press.